Actin isoform expression patterns in adult extracardiac and cardiac rhabdomyomas indicate a different cell of origin.

Rhabdomyomas are rare striated muscle-type tumors arising in the heart or in soft tissues. Using a monoclonal antibody specific for the cardiac isoform of α-actin (α-cardiac actin, α-CAA), differential expression patterns in striated muscle tissues were reported previously. The purpose of the present study was to determine whether the α-actin isoform specificity is maintained in rhabdomyomas according to their origin, comparing extracardiac to cardiac rhabdomyomas.